//
// Optimized for minimal code size.

#include "md5.h"

#include <stdio.h>
#include <string.h>

#define rol(bits, value) (((value) << (bits)) | ((value) >> (32 - (bits))))

static const char Kr[64] =
{
	7, 12, 17, 22,  7, 12, 17, 22,  7, 12, 17, 22,  7, 12, 17, 22,
	5,  9, 14, 20,  5,  9, 14, 20,  5,  9, 14, 20,  5,  9, 14, 20,
	4, 11, 16, 23,  4, 11, 16, 23,  4, 11, 16, 23,  4, 11, 16, 23,
	6, 10, 15, 21,  6, 10, 15, 21,  6, 10, 15, 21,  6, 10, 15, 21
};

static const int KK[64] =
{
	0xd76aa478, 0xe8c7b756, 0x242070db, 0xc1bdceee,
	0xf57c0faf, 0x4787c62a, 0xa8304613, 0xfd469501,
	0x698098d8, 0x8b44f7af, 0xffff5bb1, 0x895cd7be,
	0x6b901122, 0xfd987193, 0xa679438e, 0x49b40821,
	0xf61e2562, 0xc040b340, 0x265e5a51, 0xe9b6c7aa,
	0xd62f105d, 0x02441453, 0xd8a1e681, 0xe7d3fbc8,
	0x21e1cde6, 0xc33707d6, 0xf4d50d87, 0x455a14ed,
	0xa9e3e905, 0xfcefa3f8, 0x676f02d9, 0x8d2a4c8a,
	0xfffa3942, 0x8771f681, 0x6d9d6122, 0xfde5380c,
	0xa4beea44, 0x4bdecfa9, 0xf6bb4b60, 0xbebfbc70,
	0x289b7ec6, 0xeaa127fa, 0xd4ef3085, 0x04881d05,
	0xd9d4d039, 0xe6db99e5, 0x1fa27cf8, 0xc4ac5665,
	0xf4292244, 0x432aff97, 0xab9423a7, 0xfc93a039,
	0x655b59c3, 0x8f0ccc92, 0xffeff47d, 0x85845dd1,
	0x6fa87e4f, 0xfe2ce6e0, 0xa3014314, 0x4e0811a1,
	0xf7537e82, 0xbd3af235, 0x2ad7d2bb, 0xeb86d391
};

static void MD5_Transform(MD5_CTX* ctx) {
	uint32_t W[64];
	uint32_t A, B, C, D;
	uint8_t* p = ctx->buf;
	int t;

	for(t = 0; t < 16; ++t) {
		uint32_t tmp =  *p++;
		tmp |= *p++ << 8;
		tmp |= *p++ << 16;
		tmp |= *p++ << 24;
		W[t] = tmp;
	}

	A = ctx->state[0];
	B = ctx->state[1];
	C = ctx->state[2];
	D = ctx->state[3];

	for(t = 0; t < 64; t++) {
		uint32_t f, tmp;
		int g;

		if (t < 16) {
			f = (D^(B&(C^D)));
			g = t;
		} else if ( t < 32) {
			f = (C^(D&(B^C)));
			g = (5*t + 1) & 15;
		} else if ( t < 48) {
			f = (B^C^D);
			g = (3*t + 5) & 15;
		} else {
			f = (C^(B|(~D)));
			g = (7*t) & 15;
		}

		tmp = D;
		D = C;
		C = B;
		B = B + rol(Kr[t], (A+f+KK[t]+W[g]));
		A = tmp;
	}

	ctx->state[0] += A;
	ctx->state[1] += B;
	ctx->state[2] += C;
	ctx->state[3] += D;
}

static const HASH_VTAB MD5_VTAB = {
	MD5_init,
	MD5_update,
	MD5_final,
	MD5,
	MD5_DIGEST_SIZE
};

void MD5_init(MD5_CTX* ctx) {
	ctx->f = &MD5_VTAB;
	ctx->state[0] = 0x67452301;
	ctx->state[1] = 0xEFCDAB89;
	ctx->state[2] = 0x98BADCFE;
	ctx->state[3] = 0x10325476;
	ctx->count = 0;
}


void MD5_update(MD5_CTX* ctx, const void* data, int len) {
	int i = ctx->count & 63;
	const uint8_t* p = (const uint8_t*)data;

	ctx->count += len;

	while (len--) {
		ctx->buf[i++] = *p++;
		if (i == 64) {
			MD5_Transform(ctx);
			i = 0;
		}
	}
}


const uint8_t* MD5_final(MD5_CTX* ctx) {
	uint8_t* p = ctx->buf;
	uint64_t cnt = ctx->count * 8;
	int i;

	MD5_update(ctx, (uint8_t*)"\x80", 1);
	while ((ctx->count & 63) != 56) {
		MD5_update(ctx, (uint8_t*)"\0", 1);
	}
	for (i = 0; i < 8; ++i) {
		uint8_t tmp = cnt >> (i * 8);
		MD5_update(ctx, &tmp, 1);
	}

	for (i = 0; i < 4; i++) {
		uint32_t tmp = ctx->state[i];
		*p++ = tmp;
		*p++ = tmp >> 8;
		*p++ = tmp >> 16;
		*p++ = tmp >> 24;
	}

	return ctx->buf;
}


/* Convenience function */
const uint8_t* MD5(const void* data, int len, uint8_t* digest) {
	MD5_CTX ctx;
	MD5_init(&ctx);
	MD5_update(&ctx, data, len);
	memcpy(digest, MD5_final(&ctx), MD5_DIGEST_SIZE);
	return digest;
}
